In assembly line manufacturing of vehicles, it is desirable that line fittings in an air conditioning system can be secured using a power nut driver rather than using a torque wrench. For this reason, peanut or block type fittings are often used.
Various refrigerants such as R12, R134a, and CO2 have been used in the air conditioning system for the vehicle. However, environmental concerns exist. As a result, legislation has been passed by various governmental agencies of the United States and the European Union, for example, requiring that the air conditioning system operate with substantially no refrigerant leaks or permeation.
Seal structures having multiple seals have been used to militate against leaks from the fittings used in the air conditioning system. These prior art seal structures have included rubber O-rings and other elastomeric seals, for example. However, over time, such seals can degrade. Damage to the seal structure can also occur due to improper installation or handling.
An advantageous prior art block fitting with seal structure is described in Assignee's U.S. Pat. No. 7,621,568 to Schroeder et al., the entire disclosure of which is hereby incorporated herein by reference. The block fitting includes a male block portion with a first aperture receiving a tube end therein. The male block portion includes an annular shoulder surrounding the first aperture of the male block portion. The annular shoulder has an axially extending lip formed at a first end thereof. The block fitting also includes a female block portion with a first aperture receiving a tube end therein or a female integrated into a mating component. The female block portion has an annular collar surrounding the first aperture of the female block portion and cooperating with the annular shoulder formed by the male block portion. The first aperture of the male block portion and the first aperture of the female block portion are substantially concentrically aligned.
As further described in Schroeder et al., a seal structure is disposed radially inward from the axially extending lip of the male block portion and between the male block portion and the female block portion. The seal structure includes a first seal portion produced from a plastically deformable (e.g., soft) metal or plastic material, and has a free edge. The first seal portion surrounds the first aperture of the male block portion and the first aperture of the female block portion. A second seal portion is produced from an elastomer disposed on the free edge of the first seal portion. A fastener sealingly engages the male block portion and the female block portion. The fastener causes the male block portion and the female block portion to deform the first seal portion and thereby provide a primary seal between the male block portion and the female block portion. The fastener also causes the male block portion and the female block portion to cooperate with the second seal portion and provide a secondary seal between the male block portion and the female block portion. The primary seal and the secondary seal militate against a leakage of a fluid from the block fitting.
There is a continuing need for a fitting including a seal structure for use in an air conditioning system which minimizes a leaking of a refrigerant from the air conditioning system. Desirably, critical design constraints of the fitting and seal structure are optimized in order to minimize the leaking of the refrigerant from the air conditioning system.